Validation of MOPITT retrievals of carbon monoxide

Validation of the MOPITT retrievals of carbon monoxide (CO) has been performed with a varied set of correlative data. These include in situ observations from a regular program of aircraft observations at 5 sites. Additional in situ profiles are available from several short-term research campaigns. These in situ profiles are critical for the validation of the retrieved CO mixing ratio profiles from MOPITT. Ground-based spectroscopic measurements are compared to MOPITT CO total column densities to validate the observed seasonal cycles. The current validation results indicate good quantitative agreement between MOPITT and in situ profiles, with an average bias less than 20 ppbv. The same seasonal cycles are see in MOPITT and the ground-based spectroscopic data. These validation comparisons provide critical assessments of the retrievals, and continuing improvements to the retrieval algorithms are reducing the validation biases.